With the developments of computer, electronic and communication technologies, the popularity of building automation technology is increasingly widened. To satisfy the requirements for building environments, improve comfort of dwellings and realize scientific management on buildings, building equipment control systems are generally used for controlling end devices, such as lights, air conditioners, etc., to achieve the goal of environment adjustment in accordance with users' desirable standards. Therefore, the scientific management on buildings could be realized.
However, a plenty of multiple-conductor cables and cable boxes should be usually used for wiring of the existing building equipment control systems, which results in complex wirings. The complex wirings may not only raise the costs for manufacture and maintenance of the control systems and increase difficulties in fault remedy, but also deteriorate the reliability of the systems.